package edu.thu.thss.yxy.sip.event;

import java.util.EventListener;

/**
 * A call change listener receives events indicating that a call has changed
 * 
 * @author Andy Gao
 *
 */
public interface CallStateListener extends EventListener {
	/**
     * Indicates that a change has occurred in the state of the source call.
     *
     * @param evt the <tt>CallChangeEvent</tt> instance containing the source
     * calls and its old and new state.
     */
    public void callStateChanged(CallStateEvent evt);
}
